Under Icy Arctic Waters, A Fiery, Unexpected Find

By WILLIAM J. BROAD

Published: February 20, 2001

By accident, scientists peering into icy waters far beneath the North Pole have found a hidden world of fire.

Buried in sonar readings taken by a Navy submarine to create a map of the ocean floor, the scientists discovered two large volcanoes that had recently convulsed the Arctic seabed. The surprise, reported in the current issue of the journal Nature, throws light on one of the last ocean frontiers, the Arctic deep.

''We like to think we're smart people,'' Dr. Margo H. Edwards, a marine geologist at the University of Hawaii who led the discovery team, said in an interview. ''But we weren't looking for this.''

The unexpected outbursts are challenging old ideas about the geology of the earth's northern polar regions and offering a new target for an expedition later this year.

Divers now plan to visit the eruption sites in tiny submersibles to collect lava samples and to look for the bizarre creatures that often thrive in the hot springs of deep undersea volcanoes. Powered by the earth's inner heats rather than sunlight, these dark ecosystems are often surprisingly lush, with riots of giant tube worms and other strange life.

''I've studied this region for 30 years,'' said Dr. Alfred S. McLaren, a retired Navy submariner who pioneered deep Arctic mapping and is president emeritus of the Explorers Club of New York City, which is sponsoring the expedition. The opportunity to see it close up, Dr. McLaren added, ''is the realization of a dream.''

Nearly landlocked, the Arctic Ocean is about six times the size of the Mediterranean Sea. Its depths are among the most mysterious of the global ocean, mainly because of the ice, which averages about eight feet thick. This veil blocks satellites from peering into the depths and rules out the customary flotillas of research ships that bounce sound waves off the bottom to map the wilderness below.

But submarines have an unobstructed view of the sunless depths. Dr. McLaren, as commander of the Queenfish, in 1970 probed the Arctic deep with sound beams. His work foreshadowed the recent volcanic find.

After the cold war, in a first, the Navy agreed to let civilian scientists regularly use its fleet of nuclear attack submarines to study the Arctic. The Hawkbill did so in 1998 and 1999, traveling as level as possible some 700 feet beneath the ice.

Financed by the National Science Foundation, the scientists on board, using gear mounted on the submarine's hull, fired unusually fine beams of sound into the depths. At the bottom, some cut up to 600 feet into seabed ooze, enough to distinguish soft sediments from hard rock. The goal was to produce the first detailed three-dimensional maps of the dark region.

A main focus was the Gakkel Ridge, a mountainous spine that runs about 1,100 miles down the middle of the main Arctic basin, which beneath the North Pole is nearly three miles deep. Gakkel is the earth's slowest spreading midocean ridge. These volcanic rifts gird the globe like seams on a baseball, making ocean crust and, over the eons, moving the continents around like putty.

The conventional wisdom of geologic theory said the Gakkel Ridge spread far too slowly to vent molten rock from the earth's hot interior. Its spreading over the ages was seen as slow and cold.

In December 1999, months after the last Hawkbill expedition, Dr. Edwards of the University of Hawaii was still reading and analyzing the Gakkel mapping data. The Navy declassification process had slowed the work, she recalled last week. But then one of her graduate students, Gregory J. Kurras, was approached at a science meeting by Dr. Maya Tolstoy, a scientist at the Lamont-Doherty Earth Observatory of Columbia University.

Dr. Tolstoy, a seismologist, asked if the Hawaii scientists knew that the global network of sensors that track faint planetary rumbles had recently detected swarms of seaquakes on the Gakkel Ridge. Seaquakes? Hundreds of them? No, they replied, they had no idea.

Dr. Edwards and Mr. Kurras quickly called up the data from the area and found clear evidence of two large volcanoes, one exactly where the seabed had been shaking violently, unbeknownst to the submarine passing overhead. The volcanoes lay more than two miles deep and showed up in the soundings as huge mounds of hard reflective rock.

''We were jumping up and down, saying 'Look, look, look,' '' Dr. Edwards recalled. ''People had predicted that we wouldn't see any eruptions here. But there they were. A lot of science is good luck.''

Nature published the findings on Thursday. The authors were Dr. Edwards, Mr. Kurras, Dr. Tolstoy, DelWayne R. Bohnenstiehl of Lamont, Dr. Bernard J. Coakley of Tulane University and Dr. James R. Cochran of Lamont.

They report that the two volcanoes cover nearly 280 square miles of undersea terrain in a valley heavily laden with muddy sediments. ''These findings,'' they wrote, ''demonstrate that eruptions along the ultraslow-spreading Gakkel Ridge are focused at discrete locations and appear to be more voluminous and occur more frequently than was previously thought.''

Scientists say the volcanoes are a challenge for modern tectonics, which studies how the earth's crust slowly deforms. ''They're making us revamp our theories, which is good,'' Dr. Edwards said.

Dr. Cochran of Lamont agreed. ''These big flows,'' he said, ''mean either more melt is created or there is some unknown mechanism by which it is being concentrated.''

As interesting, the scientists said, is that the eruptions are potentially opening a new window into the earth's mantle, the region between the planet's cold crust and the hot core. The polar crust is unusually thin, and the new eruptions may allow unusually direct sampling of mantle rock -- a holy grail of science. ''If that's true,'' Dr. Edwards said, ''the rock chemists are going to be in hog heaven.''

The new expedition plans to find out. During a two-week voyage in late August and early September, the divers are to descend to the Gakkel in Russian Mir submersibles, which hold three people and are owned and operated by the Shirshov Institute of Oceanology in Moscow.

Never before, experts say, has the Arctic been so plumbed.

The Explorers Club and two companies, Quark Expeditions and Deep Ocean Expeditions, are using the Mirs as part of a commercial cruise to take adventure tourists to the North Pole, where for $50,000 they can dive into the abyss. American and Russian scientists are to dive on the Gakkel in as many as three scientific side trips.

The Russian nuclear icebreaker Yamal is to pound through the ice pack, and the cargo vessel Papanin is to launch the twin Mir submersibles, which filmed the Titanic for James Cameron's 1997 movie.

Dr. McLaren of the Explorers Club said the scientists intended to photograph the Gakkel and to gather samples of volcanic rock and deep creatures. Since the Arctic is the world's most isolated ocean, he added, the animals might prove to be unusual.

''It's a strange area,'' he said. ''And for me, the whole expedition is tremendously exciting. My imagination and dreams have literally been consumed with what I'm likely to encounter.''

Dr. McLaren said the discovery of odd forms of life in the deep Arctic, miles below a world of ice, would lend support to one of the wilder speculations of current science -- that the moon of Jupiter known as Europa might harbor alien swarms in a liquid ocean hidden under its icy crust.

''If we find black ecosystems there,'' he said of creatures on the Gakkel Ridge, ''it's going to increase the chance of finding them on Europa.''

Photos: Divers will use Mir submersibles to descend to the Arctic basin this summer. Dr. Alfred S. McLaren, right, is president emeritus of the Explorers Club, which is sponsoring the expedition. He says the opportunity to see the deep Arctic close up ''is the realization of a dream.'' (Chang W. Lee/The New York Times); (Alfred S. McLaren/The Explorers Club) Map of the Arctic shows the location of the Western Volcano and the launching site of the summer 2001 expedition. (Sources: Nature, National Science Foundation)